linux-kernel - Re: [PATCH] vfs: fix IMA lockdep circular locking dependency

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Message-ID: <CA+55aFwNqGN7PYsFudUKdTZikUn=Sr1tHCim3jySUfPnM4neag@mail.gmail.com>
Date:	Wed, 16 May 2012 08:13:59 -0700
From:	Linus Torvalds <torvalds@...ux-foundation.org>
To:	Eric Paris <eparis@...isplace.org>
Cc:	Mimi Zohar <zohar@...ux.vnet.ibm.com>,
	Mimi Zohar <zohar@...ibm.com>,
	linux-security-module@...r.kernel.org,
	linux-kernel@...r.kernel.org, Al Viro <viro@...iv.linux.org.uk>,
	Stephen Smalley <sds@...ho.nsa.gov>
Subject: Re: [PATCH] vfs: fix IMA lockdep circular locking dependency

On Wed, May 16, 2012 at 7:13 AM, Eric Paris <eparis@...isplace.org> wrote:
>
> So we would have no checks for anonymous mappings?  We actually do
> have some controls around them today
>
> http://www.akkadia.org/drepper/selinux-mem.html
>
> It's mostly around W+X memory.  (or was W now X memory)

Ahh, ok. So I guess that won't work.

That said, I think do_brk() can already today be used to avoid those
checks, since it does a mmap with VM_DATA_DEFAULT_FLAGS, which
includes exec if the current personality includes READ_IMPLIES_EXEC -
which is trivial yo do.

I wonder if the rwx checks could be split up too - the access
protection from the *file* is really a separate issue from the access
protection of the *mapping*, if you see what I mean.. Then we could do
it at do_brk() time too.

                      Linus

>
> Admittedly with the growing prevalence of JiT stuff we are using those
> protections less and less and less....
>
> Not certain how happy some will be to see them completely disappear....
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